karenknight9

GLK Diesel Check Engine Light and Rough Idle

My 2015 GLK Diesel is throwing a check engine light and has a really rough idle, sometimes even stalls at stop lights. It seems to have started right after I changed the fuel filter. I'm also noticing a drop in fuel efficiency and reduced engine power. Could this be related to the fuel pressure regulator or the pressure sensor? Mileage is at 98479 km. Has anyone else experienced this?

4 comment(s)

Sounds familiar. I had similar issues with my GLK after a fuel filter change too. Check engine light, rough idle, the whole shebang. Could be a pressure drop in the fuel rail. Did you make sure everything was properly seated when you replaced the filter? Its a long shot, but might be worth inspecting it again.

Good point about the fuel rail. What exactly do you mean by 'pressure drop', and how did you diagnose that on your GLK? Does it need special tools?

By pressure drop, I mean the fuel pressure isn't staying consistent, causing the engine to run poorly. The car needs a certain fuel pressure to run right. I didn't actually diagnose it myself. Took it to a workshop, and they found an error entry related to the fuel pressure regulator after the fuel filter change. They checked the fuel rail and pressure sensor but said it was a defective fuel pressure regulator.

Thanks for the info. Took it to a shop, and you were spot on it was the fuel pressure regulator. Apparently, there was an error entry after changing the fuel filter. New one cost me about 45€. Runs like new now!

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